1. Field
The invention pertains to methods and apparatus for cleaning and/or modifying data or format of continuous lengths of film or tape contained in a single reel and housed in a casing such as a cartridge or cassette.
2. State of the Art
In recent years motion picture films and magnetic tapes have become available in the form of a continuous, endless strip or length contained in a single reel housed in a casing such as a cartridge or cassette. In such single reel storage systems, a portion of the strip is withdrawn from the center of the reel and directed through guide means within the casing, past an operational opening in the casing and then returned to the outside of the reel. With motion picture film, the opertional opening is used as a projection port wherein light can be passed through the film and directed to a viewing screen. With magnetic tapes, the access opening is used to bring the tape into contact with a magnetic tape head for recording or playing back of sound messages on the tape as well as adding or erasing data stored on the magnetic tape. Through ordinary use, the tape or film contained in such reels tends to become soiled and dusty. The problem is especially acute with respect to motion picture films wherein small pieces worn from the surface of the film itself, dust particles caught by static electric charges, and soil from the projection apparatus adhere to the film and ultimately affect the quality of the projected images from the film.
Generally, known film and tape cleaning techniques of the prior art are applicable to film or tape wound on conventional reels which are designed to be used in reel-to-reel type apparatus. The tape of film is cleaned as it is run from one reel to the other. Such cleaning techniques are not suitable for endless lengths of film or tape stored on a single reel contained in a housing or casing because the film or tape does not, in normal use, extend out of the housing or casing. In U.S. Pat. No. 3,640,293, issued on Feb. 8, 1972, to Myron L. Freedman, apparatus and method for cleaning film or tape stored on a single reel housed in a cartridge are proposed, wherein a loop of film or tape is drawn out of the cartridge through the normal operational opening therein (the projection port in motion picture cartridges). The withdrawn loop is threaded around guide rollers and between a pair of motor driven cleaning brushes which rotate against the film or tape as it passes between the brushes. The apparatus disclosed in U.S. Pat. No. 3,640,293 is rather bulky and awkward due to multiple drive mechanisms needed for driving the cleaning brushes and for advancing the film or tape through the cleaning brushes. Further, the cleaning must be done in a separate operation and cannot be done in the course of normal use of the film or tape inasmuch as the loop of film or tape is withdrawn from the operating opening in the cartridge.